/* This file is part of GNUnet. (C) 2001, 2002, 2003, 2004, 2005, 2006 Christian Grothoff (and other contributing authors) GNUnet is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNUnet is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNUnet; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /** * @file util/crypto_random.c * @brief functions to gather random numbers * @author Christian Grothoff */ #include "platform.h" #include "gnunet_common.h" #include "gnunet_crypto_lib.h" #include "gnunet_os_lib.h" #include /** * Create a cryptographically weak pseudo-random number in the interval of 0 to 1. * * @return number between 0 and 1. */ static double weak_random () { return ((double) RANDOM () / RAND_MAX); } /** * Produce a random value. * * @param mode desired quality of the random number * @param i the upper limit (exclusive) for the random number * @return a random value in the interval [0,i[. */ uint32_t GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i) { #ifdef gcry_fast_random_poll static unsigned int invokeCount; #endif uint32_t ret; uint32_t ul; GNUNET_assert (i > 0); switch (mode) { case GNUNET_CRYPTO_QUALITY_STRONG: /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */ #ifdef gcry_fast_random_poll if ((invokeCount++ % 256) == 0) gcry_fast_random_poll (); #endif ul = UINT32_MAX - (UINT32_MAX % i); do { gcry_randomize ((unsigned char *) &ret, sizeof (uint32_t), GCRY_STRONG_RANDOM); } while (ret >= ul); return ret % i; case GNUNET_CRYPTO_QUALITY_NONCE: ul = UINT32_MAX - (UINT32_MAX % i); do { gcry_create_nonce(&ret, sizeof(ret)); } while (ret >= ul); return ret % i; case GNUNET_CRYPTO_QUALITY_WEAK: ret = i * weak_random (); if (ret >= i) ret = i - 1; return ret; default: GNUNET_assert (0); } return 0; } /** * Get an array with a random permutation of the * numbers 0...n-1. * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive) * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise * @param n the size of the array * @return the permutation array (allocated from heap) */ unsigned int * GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n) { unsigned int *ret; unsigned int i; unsigned int tmp; uint32_t x; GNUNET_assert (n > 0); ret = GNUNET_malloc (n * sizeof (unsigned int)); for (i = 0; i < n; i++) ret[i] = i; for (i = n - 1; i > 0; i--) { x = GNUNET_CRYPTO_random_u32 (mode, i+1); tmp = ret[x]; ret[x] = ret[i]; ret[i] = tmp; } return ret; } /** * Random on unsigned 64-bit values. * * * @param mode desired quality of the random number * @param max value returned will be in range [0,max) (exclusive) * @return random 64-bit number */ uint64_t GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max) { uint64_t ret; uint64_t ul; GNUNET_assert (max > 0); switch (mode) { case GNUNET_CRYPTO_QUALITY_STRONG: ul = UINT64_MAX - (UINT64_MAX % max); do { gcry_randomize ((unsigned char *) &ret, sizeof (uint64_t), GCRY_STRONG_RANDOM); } while (ret >= ul); return ret % max; case GNUNET_CRYPTO_QUALITY_NONCE: ul = UINT64_MAX - (UINT64_MAX % max); do { gcry_create_nonce(&ret, sizeof(ret)); } while (ret >= ul); return ret % max; case GNUNET_CRYPTO_QUALITY_WEAK: ret = max * weak_random (); if (ret >= max) ret = max - 1; return ret; default: GNUNET_assert (0); } return 0; } /** * This function should only be called in testcases * where strong entropy gathering is not desired * (for example, for hostkey generation). */ void GNUNET_CRYPTO_random_disable_entropy_gathering () { gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0); } /** * Process ID of the "find" process that we use for * entropy gathering. */ static struct GNUNET_OS_Process *genproc; /** * Function called by libgcrypt whenever we are * blocked gathering entropy. */ static void entropy_generator (void *cls, const char *what, int printchar, int current, int total) { unsigned long code; enum GNUNET_OS_ProcessStatusType type; int ret; if (0 != strcmp (what, "need_entropy")) return; if (current == total) { if (genproc != NULL) { if (0 != GNUNET_OS_process_kill (genproc, SIGTERM)) GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "kill"); GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc)); GNUNET_OS_process_close (genproc); genproc = NULL; } return; } if (genproc != NULL) { ret = GNUNET_OS_process_status (genproc, &type, &code); if (ret == GNUNET_NO) return; /* still running */ if (ret == GNUNET_SYSERR) { GNUNET_break (0); return; } if (0 != GNUNET_OS_process_kill (genproc, SIGTERM)) GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "kill"); GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc)); GNUNET_OS_process_close (genproc); genproc = NULL; } GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Starting `%s' process to generate entropy\n"), "find"); genproc = GNUNET_OS_start_process (NULL, NULL, "sh", "sh", "-c", "exec find / -mount -type f -exec cp {} /dev/null \\; 2>/dev/null", NULL); } static void killfind () { if (genproc != NULL) { GNUNET_OS_process_kill (genproc, SIGKILL); GNUNET_OS_process_close (genproc); genproc = NULL; } } void __attribute__ ((constructor)) GNUNET_CRYPTO_random_init () { gcry_control (GCRYCTL_DISABLE_SECMEM, 0); if (!gcry_check_version (GCRYPT_VERSION)) { fprintf (stderr, _ ("libgcrypt has not the expected version (version %s is required).\n"), GCRYPT_VERSION); abort (); } #ifdef gcry_fast_random_poll gcry_fast_random_poll (); #endif gcry_set_progress_handler (&entropy_generator, NULL); atexit (&killfind); SRANDOM (time (NULL) ^ GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX)); } void __attribute__ ((destructor)) GNUNET_CRYPTO_random_fini () { gcry_set_progress_handler (NULL, NULL); } /* end of crypto_random.c */